1. Field of the Invention
The present invention relates to a lens array unit which may be used as an optical system for an optical reading apparatus or an LED head for an image forming apparatus, an optical head that incorporates the lens array unit, and an information apparatus that incorporates the optical head.
2. Description of the Related Art
Electrophotographic image forming apparatuses employ an LED head in which a plurality of light emitting diodes (LEDs) is aligned in a line. Likewise, scanners and facsimile machines employ an optical reading device in which light receiving elements are aligned in a line. Conventional LED heads and optical reading devices employ a rod lens array, which is an optical system capable of forming erect images of the same size as objects aligned in a line.
Some optical systems include two lens arrays each of which includes microlenses aligned straight, and form an erect image of an object. The lens arrays may be efficiently manufactured by plastic injection molding with very high shape accuracy, thereby providing high image resolution.
One problem with the aforementioned prior art optical systems is that microlenses make the entire surface of the lens array uneven and therefore it is difficult to remove dirt and stains deposited on the lens surfaces. Another problem is that the lenses are molded from a resin material and therefore the lens surfaces are sensitive to scratch.